Comparison of the otoendoscopic and microscopic anatomy of the middle ear cleft in canal wall-up and canal wall-down temporal bone dissections.

This study was designed to compare the accessibility of particular anatomical sites in the middle ear cleft in five canal wall-up and five canal wall-down temporal bone dissections, using 0 and 70 degree otoendoscopes and the microscope. In all five canal wall-up dissections, otoendoscopy gave good visualization of all sites of the middle ear cleft whereas microscopy failed to give adequate visualization of the sinus tympani and protympanum. In all five canal wall-down dissections otoendoscopy again allowed good visualization of all sites whereas microscopy did not permit visualization of the sinus tympani. It is well known that residual cholesteatoma is most frequently found in the sinus tympani, therefore this makes the otoendoscope an essential adjunct to the microscope in canal wall-up and canal wall-down surgery.